1. Field of the Invention
The invention relates to an illuminating apparatus, more particularly to an illuminating apparatus that is adapted for use in a projection display.
2. Description of the Related Art
In a conventional projection display, light from an illuminating apparatus is split, modulated and subsequently synthesized to form an image on a display screen. A known illuminating apparatus includes a single light source, the light output of which is processed by a condenser, a beam splitter, a polarization converter, etc., of a projection display so as to form an image on a liquid crystal display panel. In a projection display with a high brightness requirement, the single light source must have a high power rating, which can result in the drawbacks of high temperature and concentration of heat, and in the problem of heat dissipation.
Therefore, the object of the present invention is to provide an illuminating apparatus that is adapted for use in a projection display and that includes at least two light sources so as to be able to provide a high brightness output without the high temperature and heat concentration drawbacks commonly encountered in the prior art.
According to the present invention, an illuminating apparatus is adapted for use in a projection display that includes a liquid crystal display panel. The illuminating apparatus comprises:
a plurality of light sources, each of which is operable so as to generate light that converges at a respective focal point;
a plurality of light pipe integrators corresponding in number to the light sources, each of the light pipe integrators having an input side facing a respective one of the light sources, and an output side adapted to face the liquid crystal display panel, wherein the focal points at which the light from the light sources converge are coincident on the input sides of the light pipe integrators, respectively, the light pipe integrators converting the light incident on the input sides thereof into evenly distributed light that are radiated at the output sides thereof;
a plurality of first lenses corresponding in number to the light pipe integrators, each of the first lenses being disposed between a respective one of the light pipe integrators and the liquid crystal display panel; and
a principal condenser lens adapted to be disposed between the first lenses and the liquid crystal display panel such that the light from the first lenses converge at points on a plane of the liquid crystal display panel upon exiting the principal condenser lens.